WASHINGTON/SEATTLE, June 27 (Reuters) - The U.S.

National Transportation Safety Board said on Thursday it was

sanctioning Boeing ( BA ) for disclosing non-public details of

an ongoing investigation into a 737 MAX mid-air emergency and

would refer its conduct to the Justice Department.

The NTSB said Boeing ( BA ) had "blatantly violated" the agency's

investigative regulations by providing "non-public investigative

information to the media" and speculating about possible causes

of the Jan. 5 Alaska Airlines door plug blowout.

The move by Boeing ( BA ) has further deepened the strain between

the crisis-hit planemaker and government agencies at a time when

it is trying to avoid criminal charges being weighed by the

Department of Justice (DOJ) ahead of a July 7 deadline.

The NTSB said Boeing ( BA ) would keep its status as a party to the

investigation into the Alaska Airlines emergency but would no

longer see unpublished information produced during its probe

into the accident, which the NTSB has previously said involved

the mid-air blowout of a door plug with four missing bolts.

Industry experts say barring a manufacturer restricts its

ability to access and offer suggestions to an investigation, but

frees it to defend its technology and practices more openly.

"As a party to many NTSB investigations over the past

decades, few entities know the rules better than Boeing ( BA )," the

NTSB said.

Boeing ( BA ) did not immediately reply to a request for comment.

The NTSB said the alleged violation of its protocols took

place during a media briefing about quality improvements at its

commercial airplanes division on Tuesday in Washington State.

"A Boeing ( BA ) executive provided investigative information and

gave an analysis of factual information previously released,"

the agency said. "Both of these actions are prohibited by the

party agreement that Boeing ( BA ) signed."

During the briefing, which was held on Tuesday under an

embargo allowing contents to be published on Thursday, a senior

Boeing ( BA ) executive said the plug had been opened on the assembly

line without the correct paperwork to fix a quality issue with

surrounding rivets, and that missing bolts were not replaced.

The team that came in and closed the plug was not

responsible for reinstalling the bolts, Elizabeth Lund, Boeing's ( BA )

senior vice president of quality, added.

The NTSB said that Boeing ( BA ) had provided it with a transcript

revealing that it had provided non-public information.

"Boeing ( BA ) offered opinions and analysis on factors it

suggested were causal to the accident," it added.

DOJ SCRUTINY

In May, the DOJ said Boeing ( BA ) had violated a 2021 settlement

with prosecutors that shielded it from criminal charges over

interactions with the Federal Aviation Administration prior to

MAX crashes in 2018 and 2019 that killed 346 people.

U.S. prosecutors have recommended criminal charges be

brought against Boeing ( BA ) after finding it violated the deferred

prosecution agreement, Reuters reported on Sunday.

The DOJ has a separate criminal probe into the MAX 9 door

plug emergency.

Thursday's unusual move by the NTSB marks the latest sign of

strains between Boeing ( BA ) and the agency.

In March, NTSB Chair Jennifer Homendy said at a U.S. Senate

hearing that Boeing ( BA ) had failed to provide the names of employees

on its 737 MAX door team for two months, drawing criticism from

lawmakers. Boeing ( BA ) then quickly provided the names.

The NTSB said on Thursday that Boeing ( BA ) had portrayed its

investigation to media as a search to locate the individual

responsible for the door plug work.

"The NTSB is instead focused on the probable cause of the

accident, not placing blame on any individual or assessing

liability," the agency said.

The planemaker will not be allowed to ask questions of other

participants at an investigative hearing on August 6-7, whereas

other participants at the hearing will be allowed to do so.

The criticism of Boeing ( BA ) came after Homendy said on Tuesday

that railroad operator Norfolk Southern ( NSC ) threatened the

board, sought to manufacture evidence and failed to provide

documents during its investigation of a 2023 Ohio derailment.

Under global rules, national agencies carry out civil probes

into air accidents for the sole purpose of finding the cause and

making recommendations to improve safety in future. Such actions

are separate from any judicial probes seeking to attribute

blame.

The NTSB, which applies similar rules to other forms of

transportation, has occasionally revoked access for outside

parties, though such interventions remain rare.

In 2013, the NTSB told United Parcel Service ( UPS ) and its

pilots union they could no longer take part in the investigation

of a crash in Alabama that killed two UPS pilots.

In 2018, the agency removed Tesla as a party to an

investigation into a fatal crash involving a vehicle's

"Autopilot" system. Tesla said it had already decided to

withdraw and accused the NTSB of violating its own rules.